(1) Field of the Invention
The present invention relates to a light emitting device and a manufacturing method thereof.
(2) Description of the Related Art
A light emitting device that employs a semiconductor light emitting element (light emitting element) such as a light emitting diode is widely used because it can easily be miniaturized and also due to its high luminous efficiency. A light emitting device that employs a light emitting element may be roughly divided into two types, namely, a face-up type according to which the surface of the light emitting element where a pad electrode is to be provided is on the opposite side from the mounting substrate, and a face-down type according to which an electrode is provided on the lower surface of the light emitting element which is a surface facing the mounting substrate.
According to the face-up type, the light emitting element is mounted on a lead or the like, and the light emitting element and the lead are connected by a bonding wire or the like. Accordingly, when mounted on the mounting substrate and viewed in a plan view in a direction perpendicular to the surface of the substrate, a part of the bonding wire has to be positioned on the outside than the light emitting element, and thus there may be a limit on miniaturization.
On the other hand, with the face-down type (flip-chip type), a pad electrode provided on a surface of the light emitting element and wiring provided on the mounting substrate may be electrically connected by a connection part such as a bump or a metal pillar positioned within the range of the size of the light emitting element when viewed in plan view in a direction perpendicular to the surface of the mounting substrate. Therefore, a CSP (Chip Size Package or Chip Scale Package) may be realized where the size of the light emitting device (especially the size in plan view when viewed in a direction perpendicular to the mounting substrate) is miniaturized to a size close to that of the chip of the light emitting element.
Furthermore, in recent years, for further miniaturization or further increased luminous efficiency, a face-down light emitting device from which a growth substrate (light-transmissive substrate) of sapphire or the like is removed or the thickness thereof is reduced is used.
A growth substrate is a substrate used for growing thereon an n-type semiconductor layer and a p-type semiconductor layer for forming a light emitting element, and has an effect of increasing the strength of a light emitting device by supporting the light emitting element that is thin and has low strength. Accordingly, with a light emitting device whose growth substrate is removed or whose growth substrate is reduced in thickness after a light emitting element is formed, a resin layer is provided on the electrode side (side facing a mounting substrate) to support the light emitting element, and also a metal pillar penetrating the resin layer is formed, and the electrode of the light emitting element and wiring (wiring layer) provided to the mounting substrate are electrically connected by this metal pillar, as indicated in Japanese Unexamined Patent Application Publication No. 2010-141176 (hereinafter referred to as Patent Document 1), for example. With the resin layer including this metal pillar, the light emitting device may secure sufficient strength.
On the other hand, for example, Japanese Unexamined Patent Application Publication No. 5-299530 (hereinafter referred to as Patent Document 2) and Japanese Unexamined Patent Application Publication No. 2008-251794 (hereinafter referred to as Patent Document 3) disclose, although not with respect to a light emitting element, methods of connecting, by a metal wire, wiring on a mounting substrate and a terminal provided on the surface of a resin for external connection.